Grinding-bur.



W. A. HANCE.

GRINDING BUR.

APPLICATION men JAN. 29. I916.

Patented J une 6, 1916.

m m u w UNITED s'rArns PATENT OFFICE.

WILLARD A. HANCE, or FREEPORT, ILLiNoIs, A ssIGNfoR To smovnaMANUFACTURING COMPANY, OF FBEEIE'ORT, ILLINOIS, A CORPORATION orILLINOIS.

GRINDiNG-BUR.

Specification of Letters Patent.

Application filed January 29, 1916. Serial No. 75,151.

To all whom it may concern:

Be it known that I, WVILLARD A. HANOE, citizen of the United States,residing at Freeport, in the county of Stephenson and State of Illinois,have invented certain new and useful Improvements in Grinding-Burs, ofwhich the following is a specification, reference being had therein tothe accompanying drawing. 1

The object of this invention is to provide grinding burs which willlessen the consumption of powerand increase the output withoutincreasing initial cost nor sacrificing durability.

It is well understood that grinding burs of the common metal type arenot readily made to run precisely in a given path and that the slightestdeviation causes one bur to cut its companion. It is also common toprovide means for retarding the discharge from the burs. To preventinitial injury by the burs and to retard delivery are results oftensecured by closing the grooves of the burs at the margins of the latterby integral metal forming a smooth faced ring to meet the smooth surfaceof the companion bur and prevent contact of the grinding teeth. Thisexpedient is effectual, but with certain materials it undesirablyreduces the output and increases the power used in running the mill. Ihave found that by closing in the way suggested the outer ends of someof the grooves, on all sides of the axis, and leaving intermediategrooves open, we have all the advantages, and none of the disadvantagesof the continuous ring. In grinding oats, for example, the gain is verygreat.

For illustration annular disk burs are shown although conical burs maybe used.

In the drawings, Figure 1 is aplan view showing one working face of anannular bur having alternate grooves outwardly closed by integral metalwhich can be con-' sidered as part of a broken marginal ring. Fig. 2 isan edge view of a portion of two coacting burs of similar construction.Fig. 3 is a section .on the. line 33, Fig. 2. Fig. 4 shows a segment ofa disk bur in which every third groove is closed at the bu'rs periphery.Fig. 5 illustrates two consecutive closed grooves alternating with asingle opeii groove.

In Figs. 1 and 2, A, A designate the bodies of two coacting burs ofannular disk form. Each has the usual general arrangement of tangentialribs and each has its inner annular portion beveled from theWorkingface' toward the inner margin of the ring, and has at regularintervals a rib extended inward to said margin to form a large feedingand breaking rib B the edge of which recedes but slightly fromtheworking plane. The intermediate ribs C do not extend to that innermargin, and on the nonbeveled portion of the ring have their edges onthe two plates quite as efieotually as the old continuous rings of whichthese mayv be considered as remaining segments. At the same timematerial between the rings escapes from alternate grooves and isretained in, intermediate grooves. It is found that practically materialdoes not fill and remain in the closed grooves while passing rapidly outof the open grooves, but that material is carried from groove to groove,material which enters the inner end of a particular groove, open orclosed, passes from groove to groove owing to the rotation, and isdelivered from a groove at some distance from the groove which it firstentered. The material is therefore. of practically uniform fineness whendelivered, and because the plates may run very close together, and yetdeliver rapidly it is always finely ground. It is not indispensable thatsingle closed and open grooves alternate. Two open grooves may alternatewith single closed grooves as in Fig. 4 or with single open grooves asin Fig. 5. Other similar changes may be made,

one or more closed grooves alternating with Patented June 6, 1916. r

working face provided With grooves separated by narrow grinding ribs,some of the grooves at short distances from each other being closed attheir outer ends only by integral metal forming peripheral bearingsurfaces substantially in the plane of the working edges of the ribswhile intermediate grooves are open at their outer ends.

2. A grinding bur having the annular peripheral portion of its Workingface provided with thin tangential grinding ribs many of which extend,distinct from their companions, to the periphery of the bur whileintermediate ribs are integrally connected at their outer ends bysegments having substantially the same height as theribs.

3. A grinding bur having in the annular outer part of its working facetangential grooves separated only by thin grinding ribs, said grooves atshort intervals around the periphery of the bur being closed at theirouter ends only by integral metal forming bearing surfaces to preventmutual injury of the ribs of oo-acting burs and obstructing the outwardflow of material in XVILLARD A. HANCE.

Vitnesses J. F. DITTMAN, C. L. SAGE.

@opies of this patent may be obtained for five cents each, by addressingthe Commissioner of ratents. Washington, D. C.

